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This compliant solution ensures that the loop counter computation involves numbers less than 224 48 (that is, 281,474,976,710,656).
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1e+16
1e+16
1e+16
1e+16
1e+16
1e+16
Compliant Solution
This compliant solution uses the Bignum module to ensure precise computation. The Bignum module is available in CPAN, but became part of Perl's standard library for version 5.8.
| Code Block | ||||
|---|---|---|---|---|
| ||||
use bignum;
my $x = 10000000000000000; # 1e+16
for (my $y = $x; $y <= $x + 5; $y += 1) {
print "$y\n";
}
|
On a 32-bit machine, this program terminates normally after printing the following:
10000000000000000
10000000000000001
10000000000000002
10000000000000003
10000000000000004
10000000000000005
Risk Assessment
Failing to understand the limitations of floating-point numbers can result in unexpected computational results and exceptional conditions, possibly resulting in a violation of data integrity.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
INT01-PL | medium | probable | high | P4 | L3 |
Bibliography
| [Gough 2005] | Section 8.6, "Floating-point issues" |
| [IEEE 754 2006] | |
| [CPAN] | Florian Ragwitz, bignum |
| [Meta CPAN] | perlnumber |
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